Preheat oven to 450 degrees F. Line a sheet pan with parchment paper and set aside.
Brown the ground sirloin. Stir in the dry taco seasoning and about half of the taco skillet sauce. Allow to simmer for a few minutes and remove from heat.
Meanwhile in a large sauce pan heat one tablespoon of the oil over medium high heat. Stir in the rice and salt and cook for a few minutes to lightly toast the rice. Stir in the water and the remaining half of the taco skillet sauce. Bring to a boil and reduce heat to low. Cover the pan and allow the rice to simmer until all the liquid is absorbed, about 18 minutes.
Stir the cooked rice, browned taco meat and shredded cheese together. Divide the filling evenly among the six tortillas. Roll into burritos.
Place the filled tortillas seam side down on the parchment paper lined sheet pan. Microwave the remaining tablespoon of oil together with the butter. Brush the melted oil and butter mixture evenly over the tops and sides of the chimichangas.
Bake the chimichangas in the oven until evenly browned, about 15 minutes.
Serve the chimichangas with a variety of toppings: shredded lettuce, diced tomatoes and fresh avocado, pickled jalapeños, sour cream and salsa.